Lets say 5 seconds run off the clock for each play. The defense has 1 TO, 1st down has just finished, the clock is running and there is 2:04 left in the game.
Scenario 1
Defense takes timeout - 2:04 on clock, 2nd down
Offense runs ball, 1:59, 3rd down clock stops for 2 min warning
Scenario 2...